As a math major, I find the abundant reliance on mathematical models by modern economists absurd. To me it seems that economists suffer from math/physics envy (in that a lot of the mathematical models they use are borrowed from physics with minor adjustments.)
The problem with trying to model a complex system such as the economy - which is comprised of hundreds of millions of participants, all with a mind of their own - is the enormous nonlinearities involved. The nonlinearity translates to significant sensitivity of the output of a certain model to initial inputs. In other words, a small error in the input leads to the rapid evolution towards massively erroneous results. Or in the language of differential equations & dynamical systems, there are huge bifurcations.
The adverse effect of this can generally be minimized when an individual, or even a company, attempts to make decisions based on quantitative methods, because their inputs represent data based on individuals with which they are more intimately related (themselves, their clients, or just a smaller subset of the entire population in general.) What I find troubling is that modern economists are responsible for formulating our economic policy, and they utilize the aforementioned methods by applying them to the entire population in order to maximize overall utility - ie "the greater good."
Empirically, modern economics certainly does not have a very good track record. Perhaps it's time for an evaluation of the field as a whole - a field that has become a joke, to be quite honest.